Hummer H2. Manual — part 1599

Gauge Installation and Removal .

4. Turn ON the ignition, with the engine OFF.

5. Command the fuel pump relay ON with a scan tool.

6. Observe the fuel pressure gauge with the fuel pump

commanded ON.

Is the fuel pressure within the specified range?

IMPORTANT:

z

The fuel pump relay may need to be
commanded ON a few times in order to obtain
the highest possible fuel pressure.

z

DO NOT start the engine.

335-375

kPa (48-

54 psi)

Go to

Step 4

Go to Step 8

4

Monitor the fuel pressure gauge for 1 minute.Does the fuel
pressure decrease by more than the specified value?

IMPORTANT:

The fuel pressure may vary slightly when the fuel pump
stops operating. After the fuel pump stops operating, the
fuel pressure should stabilize and remain constant.

34 kPa (5

psi)

Go to

Step 7

Go to Step 5

5

1. Relieve the fuel pressure to the first specified value.

2. Monitor the fuel pressure gauge for 5 minutes.

Does the fuel pressure decrease by more than the second
specified value?

69 kPa

(10 psi)

14 kPa (2

psi)

Go to

Step 12

Go to Step 6

6

1. Operate the vehicle within the conditions to reproduce

the original symptoms.

2. Monitor the O2 and the Fuel Trim parameters with a

scan tool.

Does the scan tool parameters indicate a lean condition?

-

Go to

Step 9

Go to

Symptoms -

Engine

Controls

7

1. Turn OFF the ignition.

2. Relieve the fuel pressure. Refer to Fuel Pressure Relief

Procedure .

3. Disconnect the chassis fuel hose from the engine

compartment fuel pipe. Refer to Quick Connect Fitting
(s) Service (Metal Collar) .

4. Install the J 37287 Fuel Line Shut-off Adapter between

the chassis fuel hose and the engine compartment fuel
pipe.

5. Open the valve on the fuel pipe shut-off adapter.

-

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

FUEL INJECTOR COIL TEST

Circuit Description

The control module enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied
directly to the fuel injectors. The control module controls each fuel injector by grounding the control circuit via
a solid state device called a driver. A fuel injector coil winding resistance that is too high or too low will affect

6. Turn ON the ignition, with the engine OFF.

7. Command the fuel pump relay ON with a scan tool.

8. Bleed the air from the fuel pressure gauge.

9. Command the fuel pump relay ON and then OFF with a

scan tool.

10. Close the fuel feed pipe shut-off valve.

11. Monitor the fuel pressure gauge for 1 minute.

Does the fuel pressure remain constant?

Go to

Step 12 Go to Step 11

8

Is the fuel pressure more than the specified value?

427 kPa

(62 psi)

VIN Z:

375 kPa

(54 psi)

Go to

Step 12

Go to Step 9

9

Inspect the fuel feed pipe for a restriction.
Did you find and correct the condition?

-

Go to

Step 13 Go to Step 10

10

Inspect the harness connectors and the ground circuits of the
fuel pump for poor connections. Refer to Testing for
Intermittent Conditions and Poor Connections and
Connector Repairs in Wiring Systems.
Did you find and correct the condition?

-

Go to

Step 13 Go to Step 12

11

1. Turn OFF the ignition.

2. Raise the fuel rail, with the fuel lines connected. Refer

to Fuel Rail Assembly Replacement .

3. Turn ON the ignition, with the engine OFF.

4. Command the fuel pump relay ON with a scan tool.

5. Replace any leaking fuel injectors. Refer to Fuel

Injector Replacement .

Did you complete the replacement?

-

Go to

Step 13

-

12

Replace the fuel sender. Refer to Fuel Sender Assembly
Replacement .
Did you complete the replacement?

-

Go to

Step 13

-

13

Operate the system in order to verify the repair.
Did you correct the condition?

-

System

OK

Go to Step 3

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

engine driveability. A fuel injector control circuit DTC may not set, but a misfire may be apparent. The fuel
injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase
as the temperature of the fuel injector increases.

Diagnostic Aids

z

The use of Dielectric compound GM P/N 12377900 (Canadian P/N 10953529) in the fuel injector
electrical connector may eliminate a corrosion condition.

z

Monitoring the misfire current counters, or misfire graph, may help isolate the fuel injector that is causing
the condition.

z

Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the
condition.

z

Perform the fuel injector coil test within the conditions of the customers concern. A fuel injector
condition may only be apparent at a certain temperature, or under certain conditions.

z

If the fuel injector coil test does not isolate the condition perform the fuel injector balance test. Refer to
Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 .

Fuel Injector Coil Test

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Powertrain Control
Module (PCM) Connector End Views

1

Did you perform the Diagnostic System
Check - Engine Controls?

-

Go to Step 2

Go to Diagnostic

System Check -

Engine Controls

2

Observe the ECT sensor parameter with a
scan tool.
Is the ECT sensor parameter within the
specified range?

10-32°C

(50-90°

F)

Go to Step 3

Go to Step 4

3

Measure the resistance of each fuel injector
with a DMM. Refer to Testing for
Continuity in Wiring Systems.
Do any of the fuel injectors display a
resistance outside the specified range?

11-14

ohm

Go to Step 6

Go to Diagnostic

Aids

4

1. Measure the resistance of each fuel

injector with a DMM. Refer to
Testing for Continuity in Wiring
Systems.

2. Record each fuel injector value.

3. Subtract the lowest resistance value

from the highest resistance value.

Is the difference equal to, or less than, the
specified value?

3 ohm

Go to Fuel Injector

Balance Test with

Special Tool or Fuel

Injector Balance Test

with Tech 2

Go to Step 5

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL

Description

The scan tool is first used to energize the fuel pump. The fuel injector tester is then used to pulse each injector
for a precise amount of time, allowing a measured amount of fuel into the manifold. This causes a drop in
system fuel pressure that can be recorded and used to compare each injector.

5

1. Add all of the fuel injector resistance

values, to obtain a total resistance
value.

2. Divide the total resistance value by

the number of fuel injectors, to obtain
an average resistance value.

3. Subtract the lowest individual fuel

injector resistance value from the
average resistance value.

4. Compute the difference between the

highest individual fuel injector
resistance value and the average
resistance value.

5. Replace the fuel injector that displays

the greatest resistance difference,
above or below the average. Refer to
Fuel Injector Replacement .

Did you complete the replacement?

-

Go to Step 7

-

6

Replace the fuel injector or fuel injectors
that are out of the specified range. Refer to
Fuel Injector Replacement .
Did you complete the replacement?

11-14

ohm

Go to Step 7

-

7

Operate the system in order to verify the
repair.
Did you correct the condition?

-

System OK

Go to Step 2

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2